Air feeding and cooled furnace front structure



"r. H. POLAD 2,531,344

AIR FEEDING AND COOLED FURNACE FRONT STRUCTURE Nov. 21, 1950 Tho/i205Po/ad Filed Nov. 5, 1947 I N VEN TOR.

A TTORNEY.

Patented Nov. 21, 1950 UNITED STATES AER FEET-ENG Ah? D COEZLEE) FURNACEFRONT STRUCTURE Thomas H. Polad, Dowa giac, Mich, assignor to RudyFurnace Company, Dowagiac, Mich.

Application NovemberS, 1947, Serial No. '1 84J233 (Cl. lid- 189) 6Qlaims. 1

This invention relates to improvements in furnace structure. 7

The principal objects of this invention are:

First, to provide means for cooling the door and frontplate of-a hot airfurnace.

Second, to provide a furnace having air ducts therein for the admissionof cooling air through the door and pouch extension to the top of thecombustion chamber. 7 Third, to reduce the temperature of the door,front plate and pouch extension of a hot air :furnace to render the useof steel plates for the fur nace practical.

Other objects and advantages relating to details and economies of theinvention will be apparent from the following description and claims.

The drawings, of which there is one sheet, illustrate a preferred formof my furnace structure.

Fig. 1 is afragmentary front elevational view of a hot air furnaceembodying my invention.

Fig. 2 is a fragmentary vertical cross sectional view along the line 22in Fig. 1.

Most hotair furnaces are constructed with an inner combustion chamberand an outer casin which is spaced from the combustion chamber'toprovide for the passage of air to be heated around the combustionchamber. The casing is provided with a front plate defining chargingdoor and ash door openings and the combustion chamher is provided withan extension sometimes called a pouch extension which is sealed to thefront platearound the ash and charging doors to prevent the products ofcombustion from mixing with the air being heated. Since the front plateis open to the interior of the combustion h chamber along the pouchextension, it is subject to the intense heat of the fire in thecombustion chamber and in the past has been made 10f cast iron due tothe low eoefficient of expansion of iron and its resistance to heat. I g

It is my invention to provide a chambered charging door through whichsecondary air is admitted from outside the furnace casing and directedupwardly through the door and into the front of the pouch extensiontoward the top or dome of the combustion chamber. Air thus admitted tothe furnace functions to cool the charging door and the front plate andalso to act as secondary air for combustion in the top of the combustionchamber. I have found that the temperature of a furnace door andfrontplate :may be reduced between 2'50 and 300 degrees under normaloperation of the .furnace and the :combustion within the furnace.irnpr1oved means-of :my iair directing passages. The reduced Zthtd 6dtemperature of the furnace door and front plate renders it practical tomake the front plate of sheet steel rather than cast iron by reducingthe tendency of the steel to buckle and deteriorate under hightemperature,

The furnace illustrated in the drawings coinprises a casing 5 having aconventional head 2 and enclosing a fire pot or combustion chamber 3.The casing is provided with a front plate of sheet steel having an upperpanel ii and lower panel 5 joined by a band 6. The edges of the frontplate panels are connected to the sides of the casing by sealing strips1.

The upper panel 4 defines a charging opening 8 closed by my chargingdoor 9 and the lower panel 5 defines an ash opening closed by the ashdoor H]. The opening 8 in the top panel opens into the pouch extensionll of the combustion chem.- ber, the front wall of which is welded tothe up.- per panel 4 as at l2, Adjacent to the top of the opening 8 Iprovide a pouch shield !3 which ex.- tends between the sides of thepouch extension and slopes upwardly .and inwardly to within thecombustion chamber. It will be noted that the rent edge of the pouchshield is spaced slightly downwardly and inwardly from the upper edge ofthe opening 8 to provide a passage or flue it into the pouch extension.A familiar type of smoke curtain I5 is provided on the underside of thepouch shield.

I The charging door .9 for Closing the opening it consists of an outerpanel 16 having rearwardly turned flanges ll arran ed t seat agains theop panel .4 around th op n ng 8- Th outer panel 1'5 is prov ed with a par of sl v s r spacer mem ers 1.8 which are w lded ther to and projecttoward th interi r of the fu na e and serve to support the center of heinne panel ill in spaced relationship with the outer panel The sides ofthe inner panel are flanged forward-1y as at 20 and welded to the sideflanges of the outer panel l8. The inner panel is arranged to liesubstantially in the same plane as the upper panel 4 of the casing whenthe charging dQOl is closed. The upper edge of the inner panel is spaceddownwardly below the upper edge of the opening 8 to provide an openingor flue 2i regisr ig h th flue M a th trou edge of the pouch shield.

T e lower fla e l o the uter do r pa el d fines 1 s ri of ape tu es :22arran d to admit outside a to t e ch mber 2. 5 formed between the innerouter pane s o the cha ing doorfllhe panel it being subieeted to theheat oi the hrs in the combustion chamber wil heat the air in thechamber 23 causing it to rise and be directed through the flues I4 and2| to the pouch extension from where it will pass through the pouchextension to the top of the combustion chamber.

The flow of secondary air as just described will cool both panels of thecharging door and in passing through the pouch extension will cool thetop panel 4 of the furnace front and the front of the pouch extension sothat these members will not be heated to the high temperature of thecombustion chamber. The secondary air will mix with the products ofcombustion in the top of the combustion chamber to assure completecombustion and in so doing will prevent the temperature of the top wallof the combustion chamber from rising above a desirable level.

I have thus described a highly practical commercial embodiment of myfurnace and have not attempted to illustrate other possible forms orarrangements of my structure as it is felt that such modifications asmay appear practical or desirable in certain instances may be madewithout further description.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. In combination with a hot air furnace having a steel front plate anda combustion chamber closed at the top by a dome and joined to saidfront plate by a pouch extension, said pouch extension including a topwall extending generally in an upward direction from said front platetoward the dome of the combustion chamber, said front plate defining acharging opening, a pouch shield positioned in said pouch extension andsloping upwardly and inwardly from adjacent the upper edge of saidopening and defining a flue o ening into said pouch extension, saidpouch shield being spaced from the pouch top wall to provide apassageway extending generally upwardly from said flue opening towardthe dome of the combustion chamber to direct relatively cool airentering said flue opening to ards t e dome of the combustion chamber, acha ging door for closing said chargins. opening, said door havingspaced inner and o t r panels, the outer panel being rearwardly flangedto en age t e front surface of said front panel around said chargingopening and defining a s ries of a ertures through the lower flangethereof opening to the space between said door panels, said inner panelhaving side flan es welded to the side flanges of said outer panel andterminating in spaced relationship with the u per edge of said chargingopening when in closed position to define a second flue opening oppositesaid first flue.

2. In combination with a hot air furnace having a front plate and acombustion chamber closed at the top by a dome and joined to said frontplate by a pouch extension, said pouch extension including a top wallextending generally in an upward direction from said front plate towardthe dome of the combustion chamber, said front plate defining a chargingopening, a pouch shield positioned in said pouch'extension and slopingupwardly and inwardly from the upper edge of said opening and defining aflue opening to said pouch extension, said pouch shield being spacedfrom the pouch top wall to provide a passageway extending generallyupwardly from said flue opening toward the dome of the combustionchamber to direct relatively cool air entering said flue opening towardsthe dome of the combustion chamber, a charging door for closing saidcharging opening, said door having spaced inner and outer panels, theouter panel being rearwardly flanged to engage the front surface of saidfront panel around said charging opening and defining an aperturethrough the lower flange thereof opening to the space between said doorpanels, said inner panel terminating in spaced relationship with theupper edge of said charging opening when in closed position to define asecond flue opening opposite said first flue.

3. In combination with a hot air furnace having a front plate and acombustion chamber closed at the top by a dome and joined to said frontplate by a pouch extension, said pouch extension including a top wallextending generally in an upward direction from said front plate towardthe dome of the combustion chamber, said front plate defining a chargingopening, a pouch shield positioned in said pouch extension and slopingupwardly and inwardly from the upper edge of said opening and defining aflue along the front edge thereof, said pouch shield being spaced fromthe pouch top wall to provide a passageway extending generally upwardlyfrom said flue opening toward the dome of the combustion chamber todirect relatively cool air entering said flue opening towards the domeof the combustion chamber, a charging door for closing said chargingopening, said door having spaced inner and outer panels, said outerpanel being rearwardly flanged to engage the front surface of said frontpanel around said charging opening and defining a passageway through thelower flange thereof opening from the outside of said door to the spacebetween said door panels, said inner panel defining a second flue alongthe upper edge of said door opening opposite said first flue.

4. In combination with a hot air furnace having a front plate defining acharging opening and a combustion chamber closed at the top by a domeand joined to said front plate by a pouch extension, said pouchextension including a top wall extending generally in an upwarddirection from said front plate toward the dome of the combustionchamber, a pouch shield having its front edge spaced from the upper edgeof said charging opening, said pouch shield being spaced from the pouchtop wall to provide a passageway extending generally upwardly from saidflue opening toward the dome of the combustion chamber to directrelatively cool air entering said flue opening towards the dome of thecombustion chamber, a chambered door for closing said charging opening,the upper edge of said door defining an opening adjacent to the spacealong the front edge of said pouch shield, the lower edge of said doordefining another opening for the admission of secondary air from outsidesaid furnace to the chamber within said door.

5, In combination with a furnace comprising a combustion chamber closedat the top by a dome and provided with a front wall having a chargingdoor opening, of a door for said opening comprising outer and innerpanels spaced to provide a vertical flue coextensive with the width ofthe door, the door having air inlet openings from the exterior of thedoor to said flue at the bottomthereof and an air discharge opening atthe top of the inner panel thereof del ve g o the interior of saidcombustion chamber, and a downwardly and forwardly inclined baiflespaced from the dome of the combustion chamber and disposed with itsfront edge adjacent but below the air discharge opening of said door sothat the air is discharged from the door flue above said baffle, saidbaffle and said front wall of the combustion chamber being spaced andforming a passageway disposed to direct air leaving said dischargeopening towards the dome of the combustion chamber.

6. In combination with a furnace comprising a combustion chamber closedat the top by a dome and provided with a front wall having a chargingdoor opening, of a door for said opening comprising outer andinnerpanels spaced to provide a flue, the door having an air inletopening from the exterior of the door to said flue at the bottom thereofand an air discharge opening at the top of the inner panel thereofdelivering to the interior of said combustionchamber, and a downwardlyand forwardly inclined bafiie spaced from the dome of the combustionchamber and disposed with its front edge adjacent the air dischargeopening of said door so that the air is discharged from the door flueabove said baffle.

THOMAS H. POLAD.

